fix(cli): suggest supervise for a registered remote mesh

[davidfarah2003]

Scope

• Branch cotal up hand-registered-space guidance by registered-server locality: a non-local broker names exact cotal supervise --space <space> --server <registered-url> recovery and the corresponding cotal deliver command; a known-stale record remains removable.
• Make cotal meshes rm name that it removes this machine's registry route to the mesh.
• Add live real-broker registry-smoke cells for the remote route and a mutation fixture that proves the named remedy assertion detects a weakened branch.
• Document the recovery and record-removal boundary in the CLI and mesh-operation guides.

Verification

• pnpm smoke:meshes-registry (113 checks)
• pnpm mutation-proof --config implementations/cli/smoke/fixtures/remote-supervise-remedy.mutations.json (1/1 killed)
• pnpm changeset status
• pnpm typecheck
• pnpm build

Bounds

• The smoke fixture broker briefly binds 0.0.0.0; this is test-only, so the smoke can reach it through a real non-loopback address.
• A remote broker registered under a literal loopback spelling (for example, an SSH tunnel) retains removal-first advice; this change treats literal loopback as local.

Closes #757

[davidfarah2003]

Closing as superseded: main's cotal up remedy path now suggests cotal supervise when the control plane is degraded (implementations/cli/src/commands/up.ts), and #849 landed the remote-mesh authority explanation for the registered-remote case (#757's scenario). The branch is ~204 changed files behind current main; if a residual hint gap remains for the exact registered-remote flow, a fresh small PR against current up.ts is the cheaper path.